taxonID	type	description	language	source
C82A87F6D445F32BFE23FD92378FFBC8.taxon	description	Yeast lacks the 7 DR gene, and Δ 5,7 - eposterol can be used as a substrate for the heterologous 7 DR enzyme (Fig. 1). The two Aa 7 DRs were heterologously expressed in S. cerevisiae for functional characterization. Aa 7 DR 1 and Aa 7 DR 2 were cloned into the expression vectors pESC-HIS-Aa 7 DR 1 and pESC-HIS-Aa 7 DR 2, then were transformed into S. cerevisiae strain Cen. pk 2 - 1 D. Compared with the empty-vector-transferred control, the yeast strain expressing Aa 7 DR 1 yielded two prominent products (peaks 1 and 2) at comparable levels (Fig. 6 A). While there were no significant differences between pESC-His-Aa 7 DR 2 and the control. To determine the structural features of Aa 7 DR 1 products a large-scale fermentation (7 L) was used to accumulate enough products. The products were isolated and purified using open silica gel column and semi-preparative reversed-phase high performance liquid chromatography. The structures of p 1 were confirmed as ergosta- 5,22 - dien- 3 β- ol by 1 H and 13 C-NMR data (Supplemental Figures S 6 and S 7; Supplemental Table S 6). Product p 2 was identified as campesterol by 1 H-NMR and comparison with the standard. We determined Aa 7 DR 1 possessed 7 - dehydrocholesterol reductive function to reduce Δ 5,7 - eposterol and ergosterol at Δ 7 position. The indirect product campesterol (p 2) was further catalyzed by endogenous gene erg 4 on ostreasterol (Fig. 5).	en	Wang, Yunpeng, Xiong, Wenbo, Chen, Yidu, Zhu, Min, Liang, Jincai, Li, Yu, Huang, Jia, Huang, Liufang, Liu, Zhongqiu, Ji, Aijia, Duan, Lixin (2021): Transcriptomic investigation of the biochemical function of 7 - dehydro- cholesterol reductase 1 from the traditional Chinese medicinal plant Anemarrhena asphodeloides Bunge. Phytochemistry (112954) 192: 1-9, DOI: 10.1016/j.phytochem.2021.112954, URL: http://dx.doi.org/10.1016/j.phytochem.2021.112954
